1. Field of the Invention
The present invention relates to a VBR (variable Bit Rate) data processor and its processing method for a DVD (Digital Video Disc) player, and in particular to an improved VBR data processor for a DVD player which is capable of processing a data having a VBR without using an additional memory for storing a video data and a control logic circuit for controlling the memory.
2. Description of the Conventional Art
FIG. 1 is a block diagram illustrating a conventional VBR data processor for a DVD player.
As shown therein, the conventional VBR data processor for a DVD player includes a pickup apparatus 102 for reading a data written on a disc 101, a servo unit 103 for driving the pickup apparatus 102 and for amplifying the data read from the disc 101, a demodulation and error correction unit 104 for demodulating the data from the servo unit 103, correcting the error of the demodulated data, and outputting a data DATA1, a memory 105 for storing the data DATA1 from the modulation and error correction unit 104 in a predetermined portion of the memory 105 in accordance with a write address WA, an MPEG (Motion Picture Experts Group) decoder 107 for storing a data DATA2 from the memory 105 in an internal memory, coding the data for a motion picture compression, generating a video data VIDEO and an audio data AUDIO, and outputting a data request signal DATA.sub.-- REQ, and a VBR controller 106 for supplying the write address WA to the memory 105 and a read address RA to the memory 105 in accordance with the data request signal DATA.sub.-- REQ from the MPEG decoder 107 so that the data DATA2 is outputted to the MPEG decoder 107, for comparing the write address WA with the read address RA, and outputting a back track jump signal JUMP to the servo unit 103.
The VBR controller 106 includes a write address generator 106a for generating a write address WA, a read address generator 106b for generating a read address RA, and a comparator 106c for comparing the write address WA with the read address RA.
The operation of the VBR data processor of a conventional DVD player will now be explained with reference to the accompanying drawings.
As shown in FIG. 2, the data written on the disc 101 is classified into a synchronous pattern region for a synchronization of a block and sector, a region for an identification number ID of the block or sector, and a user data region which is an ordinary data region.
In the CBR (Constant Bit Rate) which is contrary to the VBR, the data transmission rate is constant, and the motor for driving the disc is rotated at a predetermined speed for the transmission rate of the data.
However, since the transmission rate of the date is variable, the motor is rotated at a predetermined speed for the maximum data transmission rate. If the apparatus as shown in FIG. 1 has the maximum data transmission rate, there are no problem. But, if the apparatus, as shown in FIG. 1 has a low transmission rate, the data read from the disc 101 may be over-flown.
In order to store the over-flown data, the memory 105 is additionally needed. In addition, if the data is over-flown from the memory 105 as well, the servo unit 103 must move the pickup apparatus 102 from the current position of the disc to another position which has been read previously by the pickup apparatus 102.
While the pickup apparatus 102 is being moved to the another position, the previously read data are disregarded. In addition, the MPEG decoder 107 had already read the data stored in the memory 105. When the pickup apparatus 102 is moved to the current position, the memory 105 stores the data read by the pickup apparatus 102, and the above-described processes are repeated.
The VBR controller 106 stores the identification number ID at the position where the data DATA1 was recognized, checks the write address WA and read address RA from the memory 105, and outputs the back track jump signal JUMP to the servo unit 103 if the data is predicted to over flow from the memory 105.
When the pickup apparatus 102 is moved to the previous position by one track from the current position, the data read by the pickup apparatus 102 while the pickup apparatus 102 was being moved to the original position are not stored in the memory 105.
When the pickup apparatus 102 reaches the original current position again, the VBR controller 106 checks the identification number ID of the data DATA1 read by the pickup apparatus 102 and outputted from the demodulation and error correction unit 104. If the identification number ID of the data DATA1 is the same as the identification number ID of the data finally written in the memory 105, the VBR controller 106 writes the data DATA1 into the memory 105.
However, since the conventional VBR data processor for a DVD player additionally needs a large memory having a capacity of 4M bytes, a control logic circuit for controlling the memory, and another memory for decoding data by using the MPEG decoder multiple memory is disadvantageously needed. In addition, since the conventional VBR data processor needs additional ICs, it is impossible to fabricate a compact system, thus increasing the fabrication cost.
Furthermore, since it is necessary to provide a controller for controlling the additional memory, the number of parts is increased, further increasing the fabrication cost.